The invention relates in general to a storage flange for an electrical and/or optical cable and in particular, to a cable spool having an integral end storage flange spaced away from a periphery of an outer end flange for holding a cable end available for testing, but out of contact with a surface upon which the spool is positioned.
It is well known that cable, in particular communications cable, whether having electrical conductors or fiber optic waveguides therein, is commonly stored on spools prior to and sometimes during use. Conventional spools for storing communications cable, however, suffer from a number of shortcomings. For instance, cable is typically wound about a cylindrical drum of a spool in multiple layers. The static coefficient of friction between the surface of the cable and the drum surface, as well as among the various cable surfaces brought into contact with each other when the cable is wound, effectively prevents the cable from being removed from the drum by any method other than unwinding. It should be appreciated, however, that when the cable is almost completely unwound from the drum, for instance when there is only a portion of one winding layer of cable remaining on the drum, the drum is held locked and a relatively large tensile force is applied to the cable, the cable may slide free of the drum. If the cable is being strung directly from the cable spool and it is necessary to hold it in tension, this, of course, can lead to difficulties in its installation.
One of the methods of preventing cable slippage on the drum is to anchor the cable by taking a first or inner end of the cable and drawing it through an aperture either in the drum or in the flange of the drum, as is disclosed in U.S. Pat. No. 2,811,322. Other patents, for instance, U.S. Pat. Nos. 3,743,210, 4,084,767, 4,387,863 and 4,715,549, disclose spools having means for locking the end of the cable to a flange. While those cable spools, which adequately anchor the cable and spools such as that shown in U.S. Pat. No. 2,417,587 to Damstra may hold an end of the cable firmly with respect to the cylindrical drum, the inner cable end is left exposed. If the reel or spool is placed on a surface, the end of the cable may be brought into contact with the surface where it may become abraded or damaged. While, for certain types of flexible tension members such as the clothesline of U.S. Pat. No. 2,417,587, this presents little problem, delicate communications cables, in particular those having optical fibers and especially single mode optical fibers, may be damaged quite easily by unwanted abrasive contact with surfaces which may render the fibers useless. The prior art cable spool constructions fail to protect the fixed end of the cable because they allow it to be contacted by outside agents.
By the same token, since the type of cable being discussed is communications cable, it is often desirable, if not necessary, to test the cable as it is being installed. For instance, fiber optic communication cable may be unrolled from the cable spool and connected to a repeater or to another cable via a fiber optic coupler. If the ends of the optical fibers are not aligned with each other precisely, the light losses in the coupler may be so great that they render the connection useless. One way to test for such losses is to inject a signal into the inner end of the cable in order to measure the effective impedance of the joint of the cable with another cable or device. Thus, it is important that the inner end of the cable be held available for connection while substantially shielding it from unwanted contact which may damage it. Unfortunately, none of the prior art cable spools are able to perform these multiple functions.
What is needed is a cable spool which firmly anchors an inner end of the cable to the spool and protects the inner end from damage while providing ready and easy access to the inner end to allow the cable to be electrically or optically tested quickly and easily.